The present invention relates to a multi point bolting mechanism, and in particular, but not exclusively, to a locking bolting mechanism for providing a multi point bolting action to secure a leaf within a frame.
Bolting mechanisms providing a multi point bolting action are well known for fastening hinged doors, windows and other types of leaf within a frame, with considerably more security than if a single point bolt action is used. A multi point bolting action may be particularly desirable on doors at the entrances to buildings, on secure containers, the rear doors of vans and lorries and for many other applications. Three point bolting mechanisms are particularly common, although mechanisms with two, four or more bolting actions are known.
In a three point bolting mechanism mounted on or in a door hinged to swing about an upright axis, a main bolt is usually slidable from the mechanism into a recess or fitting of the unhinged upright side of the door frame. A three point bolting mechanism usually then provides additional top and bottom bolting actions by sliding top and bottom bolts into recesses or fittings of the top and bottom horizontal sections of the door frame. The top and bottom bolts are mechanically coupled to and operate simultaneously with the main bolt.
A simplified illustration of a three point bolting mechanism of the prior art is shown in FIG. 1. The following description supposes that the bolting mechanism is mounted on a main face of a door hinged about a vertical axis within a rectangular frame.
A toothed drive gear 10 is rotatable about a horizontal axis by means of a shaft passed through a central shaft hole 12, the shaft being turned by a handle, a push bar or other device, The top of the drive gear is in meshed engagement with a toothed rack portion 14 of a lower edge of a horizontally extended main bolt 16, which extends through an aperture in a vertical side 18 of the mechanism casing 20. The main bolt is constrained to move horizontally. Rotation of the drive gear causes the main bolt 16 to move horizontally, extending further out of or retracting back into the casing 20 and therefore providing a bolting action into a recess or fitting of an unhinged upright side of the rectangular frame. A toothed rack portion 22 of an upper edge of the main bolt 16 is held in meshed engagement with an idle gear 24 which is of a similar size and is mounted in the same plane as the drive gear 10. The idle gear, mechanically linked to the drive gear by means of the main bolt, counter rotates when the drive gear rotates.
One side of the drive gear 10 engages a toothed rack portion 26 of a side of a vertically extended lower pushrod 28. The lower pushrod passes through a close fitting aperture in a bottom side 30 of the casing 20. When the drive gear 10 rotates, the lower pushrod is driven further out of or retracted into the casing, providing a bolting action into the rectangular frame by means of a bolt positioned near the bottom of the door and mechanically linked to the lower pushrod. The idle gear 24 similarly acts on a toothed rack portion 32 of one side of a vertically extended upper pushrod 34, which is constrained to move vertically, providing a bolting action into a top part of the frame.
The prior art three point bolting mechanism described above may be provided with a key cylinder or other key accepting mechanism which acts on some part of the bolting mechanism in order to provide a secure locking procedure. However, because the drive and idle gears of the bolting mechanism lie in substantially the same vertical plane, below and above the toothed rack portions of the main bolt, the casing of the mechanism described needs to be quite long from top to bottom. The addition of a key cylinder and the associated mechanisms above the slave gear or below the drive gear would make the casing even longer. A long casing is particularly inconvenient if the mechanism is to be mounted inside a door in a mortice configuration, because a very long slot must be cut into the door edge. This is a time consuming process when fitting the mechanism into the door, and moreover may weaken the door unduly.
It would therefore be desirable to provide a multi point bolting action mechanism in a more compact configuration, so that a key cylinder and other desirable mechanisms may be incorporated while maintaining a mechanism casing of convenient size.
Accordingly, the present invention provides a mechanism for providing a multi-point bolting action to secure a leaf moveable within a frame, comprising:
a drive gear and an idle gear mounted to rotate about substantially the same axis, said idle gear being arranged to rotate in one sense when said drive gear rotates in the other sense;
at least one first member having a rack which is held in intermeshing engagement with said drive gear, said at least one first member being arranged to move between a thrown position and a retracted position when said drive gear rotates;
and at least one second member having a rack which is held in intermeshing engagement with said idle gear, said at least one second member being arranged to move between a thrown position and a retracted position when said idle gear rotates.
Advantageously, the mechanism further comprises a gear train arrangement comprising at least two further gears, a first of the further gears being in intermeshing engagement with said drive gear, and a second of the further gears being in intermeshing engagement with said idle gear.
Advantageously, the at least two further gears comprise third and fourth gears, said third gear being in intermeshing engagement with said drive gear and with said fourth gear, said fourth gear being in intermeshing engagement with said idle gear and with said third gear.
Conveniently, at least one of said members comprises a pushrod that is connected to a bolt, said pushrod and said bolt being arranged to secure said leaf within said frame when said drive gear rotates in one sense, and to release said leaf when said drive gear rotates in the other sense.
Advantageously the mechanism further comprises:
a casing housing the mechanism, the casing comprising a fore-end plate which is located adjacent to the frame when the leaf is positioned fully within the frame;
a bezel plate that is removably mounted to the fore-end plate;
a strike head that is arranged to be rotatable about and moveable along a strike head axis substantially normal to said fore-end plate, said strike head being arranged to move within an aperture in said fore-end plate and within a corresponding aperture in said bezel plate, and being arranged to restrain or release at least one of said members by an action of said frame on said strike head, said aperture in said fore-end plate allowing rotational motion of said strike head about said strike head axis and said aperture in said bezel plate restricting the rotational motion of said strike head about said strike head axis.
Conveniently, said aperture in said fore-end plate is circular and said corresponding aperture in said bezel plate is rectangular.
Advantageously, the mechanism further comprises a strike body arranged to be movable along said strike head axis between a retracted and an extended travel limit, said travel limits being defined relative to said casing, wherein said strike head is connected to said strike body by threaded means aligned along said strike head axis such that rotation of said strike head about said strike head axis alters the relative positions of said strike head and said strike body in the direction of said strike head axis.